Mask



FIG. 1 is a left side elevation view showing the ornamental design of amask;

FIG. 2 is a front side elevation view thereof;

FIG. 3 is a right side elevation view thereof;

FIG. 4 is a top plan view thereof;

FIG. 5 is a bottom plan view thereof;

FIG. 6 . is a back side elevation view thereof; and,

FIG. 7 is a perspective view thereof.

CLAIM The ornamental design for a mask, as shown and described.